The Smectic–Isotropic Transition of P3HT Determines the Formation of Nanowires or Nanotubes into Porous Templates

Abstract

We present the simple and controllable fabrication of ordered arrays of poly(3-hexylthiophene) (P3HT) solid nanowires and hollow nanotubes by infiltrating the molten polymer into AAO nanopores at temperatures promoting partial (260 °C) and complete (280 °C) wetting regimes, respectively. We show that such wetting regimes (and thus the formation of nanowires or nanotubes) are associated with a different internal structure in the P3HT melt. At 260 °C, the P3HT organizes into a smectic mesophase. Thus, the translational motion of the P3HT molecule through the phase-separated structure would involve an enthalpic penalty, which prevents the molecular diffusion required for achieving the complete wetting regime. Consequently, the P3HT wets the nanopores in partial wetting regime, so that solid nanowires are formed. In contrast, the melt is structurally isotropic at 280 °C, which promotes the complete wetting regime, yielding nanotubes. Such a smectic mesophase is also present in P3HT confined into 350 nm in dia...